Watercraft are commonly powered by inboard or outboard motors. The motor includes a water propulsion device which is powered by an internal combustion engine. The motor also typically contains, at least in part, an electrical system. As is well known, an ignition system, which forms a part of the electrical system, fires one or more ignition elements, or spark plugs, which correspond to the combustion chambers of the engine, thereby igniting the air and fuel mixture in each combustion chamber. The watercraft also typically includes several lights and gauges commonly powered by the electrical system.
With reference to FIG. 1, a standard electrical system commonly utilized in watercraft is illustrated. As shown, the circuitry consists of a hull-based circuitry portion A' and a motor-based circuitry portion B'. The motor-based circuitry portion B' in the illustrated embodiment includes a generator circuit 257 and an ignition circuit 248. The generator circuit 257 generally comprises a charging coil 254 and a rectifier 256. The ignition circuit 248 includes a plurality of spark plugs 244a-d, and at least two pulsar coils 270, 272. The hull-based circuitry portion A' in the illustrated example includes a battery 252, a main switch 238 and a kill switch 239. The hull-based circuitry portion A' also includes a plurality of electrical equipment 234, such as switches, gauges and other indicators which are powered by the electrical system.
In the embodiment of FIG. 1, the hull-based circuitry portion A' and the motor-based circuitry portion B' are connected together in a known manner, such as, for instance, by using common quick-connect connectors 250. Moreover, because a current potential of the battery 252 is very high, a main fuse 262 is provided between the two portions A', B' for protecting both the ignition circuit and the electric equipment 234.
A feeder circuit 259 is connected to the charging circuit 257 for feeding both the ignition circuit 248 and the electric equipment 234. This feeder circuit 259 enters the hull side of the watercraft through a connector 250 and is connected to the electric equipment 234 in the hull through the main switch 238. The feeder circuit 259 is also connected to the ignition circuit 248 through a connector 250 in the outboard motor side. Desirably, an additional accessory fuse 264, having a lower current rating than the main fuse 262, is provided for protecting the electric equipment 234.
While this electrical system allows the same circuit to power both the ignition circuit 248 and the electrical equipment 234, the current tolerance for the ignition circuit 248 is typically higher than that of the electric equipment 234. Accordingly, the current rating for the accessory fuse 264 is calculated to protect the electric equipment 234 while disregarding the ignition circuit requirements. This arrangement is disadvantageous because the electric equipment then sets the level of current which may be passed on to the ignition circuit at a level substantially below the current tolerance of the ignition circuit.
Moreover, with a conventional engine having a DC-CDI (i.e., direct current--capacitor-discharge ignition) type of ignition circuit, an engine-hunting (or adjustment) results from an unstable charge level in the ignition circuit because of hull vibrations. Specifically, the hull vibrations may cause the main switch to chatter and disrupt the electrical circuitry. Also, corrosion or rust may affect the connectors, thereby reducing the reliability of the electrical system feeder which does not have a redundancy built in.
An improved power circuit which overcomes the above-stated problems is therefore desired.